Effect of Days Open on Economic Aspects of Current Lactation

Abstract

Multiple regression equations were derived from data for 6,351 Holsteins for first lactations and 17,978 later lactations. Within herds each day open between 40 and 140 days of lactation resulted in an average of 4.5 kg less annual milk during current lactations of first-calf heifers and 8.6 kg less for cows in later lactations.